A team of Stanford engineers have made a simple computer inside a living cell, where it could detect disease and warn of toxic threats.
The startling achievement, unveiled in Friday’s issue of the journal Science, takes us to a new frontier — where nature’s instruction manual is being programmed to carry information.
“We’re going to be able to put computers inside any living cell you want,” said lead researcher Drew Endy of Stanford’s School of Engineering. “Any place you want a little bit of logic, a little bit of computation, a little bit of memory — we’re going to be able to do that.”
The computers could deliver true-false answers to virtually any biological question that might be posed within a cell. For instance: Is toxic mercury present? It could detect it.
Also: They can count. This would be a useful tool when treating diseases like cancer, where cells divide uncontrollably. Suppose a liver cell carries a counter that records how many times it divides. Once the counter hits 500, for instance, the cell could be programmed to die.
Endy’s work “clearly demonstrates the power of synthetic biology and could revolutionize how we compute in the future,” said UC Berkeley biochemical engineer Jay Keasling. He is director of the Synthetic Biology Engineering Research Center that helped support research at Stanford.
These cell-based computers will be a different kind of computer, Endy said.
“We’re not going to replace the silicon computers. We’re not going to replace your phone or your laptop. But we’re going to get computing working in places where silicon would never work,” he said.
Conceptually, it’s like electronics, where a transistor controls the flow of electrons along a circuit.
But biology is the basis for what the team calls a “transcriptor,” which controls the flow of an important protein as it travels along a strand of DNA like an electron on a copper wire.
Transcriptors are a biological version of electrical engineers’ “logic gates” — the building blocks of digital circuits that send and receive signals.
Endy, recruited to Stanford from the Massachusetts Institute of Technology, is a builder — a civil engineer who started with boyhood Erector Sets and Legos, later working on bridge repair projects for Amtrak.
Now he’s building with the stuff of life to use it as a technology platform.
“Biology is not just a science of discovery, but also a technology for making things,” he said.
The team’s transcriptor-based gates are the third and final component in a 10-year drive to the biological computer.
Last year, the team delivered the other two core components of a computer. The first was a type of rewritable digital data storage within DNA. Information can be stored inside cells by flipping DNA sequences back and forth between two possible orientations to represent and store “0” and “1” that represent one “bit” of computer data.
The other was a mechanism for transmitting genetic data from cell to cell, a biological Internet.
The creation of “logic gates” means that everything can be connected, and signals can work. Researchers who learned of the work ahead of publication are already using the gates to reprogram metabolism, according to Endy.
It is the latest step in the new field of synthetic biology where — one gene at a time — engineers strive to design and build organisms unlike anything made by Mother Nature.
A similar computer is underway at the Massachusettts Institute of Technology, where engineer Timothy Lu said he seeks to “open up biological applications that conventional computing simply cannot address.”
The internal computers could communicate by engineering cells to change noticeably.
The “simplest way is to have the cells change their smell or color,” Endy said. Students at Cambridge University and the Royal College of Art developed a “scat-o-log” by engineering E. coli bacteria to produce a full spectrum of pigments (like a box of crayola crayons), he said.
These new biological computers will be slow, Endy cautioned.
“But they’ll work in places where we don’t have computing now,” he said.